1. Field of the Invention
The present invention relates to a thrombus resolving treatment apparatus for resolving a thrombus formed in a blood vessel by using a thrombus resolvent and an ultrasonic wave.
2. Description of the Related Art
In Europe and the U.S., vascular diseases, e.g., arteriosclerosis and thrombosis, have been found very often and are increasing. In Japan as well, thrombotic ischemic heart diseases, e.g., cerebral infarction and myocardial infarction, are increasing due to the change in diet and are listed as one of the two major causes of death (the other cause is a cancer). To treat such an ischemic heart disease, a thrombectomy must be performed. The thrombectomy or vascular grafting is highly invasive to the patient's body and thus is not appropriate especially for an aged patient prone to suffer from this type of disease. A thrombus formed in a cerebral blood vessel or a cardiac coronary artery causes the infarction of cerebral or myocardial cells unless a thrombectomy is immediately performed. In particular, the former can endanger the life or cause a serious aftereffect if the thrombectomy is retarded. Hence, it is required to perform the thrombectomy as quickly as possible.
For example, thrombus resolving treatments, e.g., PTCR (percutaneous transluminal coronary recanalization), "intravenous drip", (a technique to administer a large amount of thrombus resolvent having a high concentration by drip over a long period of time), "intraarterial infusion" (a technique to administer a thrombus resolvent to a carotid through a catheter), and PTCA (percutaneous transluminal coronary angioplasty) attract attention as quick, effective thrombus treatments that are less invasive to the patient's body when compared to a surgical operation or the like. Of these treatments, according to PTCR, a catheter is inserted in a coronary artery, and a thrombus resolvent is quickly injected into the coronary artery close to the thrombus while the positions of the blood vessel and the catheter are fluoroscopically monitored by using an X-ray contrast medium. With PTCR, however, the recanalization rate of the blood vessel is low, and the problem of X-ray exposure exists. In "intravenous drip", although the blood vessel recanalization rate is comparatively high, a side effect occurs that the blood becomes hard to coagulate because of the large amount of thrombus resolvent. Furthermore, according to PTCA, the inner wall of the blood vessel is flexibly expanded by a balloon catheter. Hence, although the "blood vessel recanalization rate" is high, a thrombus reoccurrence rate is high.
Recently, the effect of the thrombus resolvent is increased by adopting both administration of the thrombus resolvent by "intravenous drip" and external ultrasonic radiation to the thrombus. Since the administration amount of the thrombus resolvent can be decreased with this method, the side effects are reported to decrease (Medical Electronics and Bioengineering, vol. 26, page 536, 1988). Even with this method, however, it is preferable to minimize the administration amount of the thrombus resolvent. For this purpose, a therapeutic ultrasonic wave must be efficiently radiated on a thrombus portion, and the effect of the thrombus resolving treatment must be monitored so that no excessive thrombus resolvent may be administered once the thrombus is completely resolved. It is also preferable that the effect of the thrombus resolving treatment can be quantitatively identified in order to perform a precise, efficient treatment.
As described above, the thrombus resolving treatment method that adopts both administration of the thrombus resolvent and ultrasonic radiation is advantageous in that it has in principle a high therapeutic effect and has a few side effects. In order to exhibit its advantage to the maximum, the therapeutic ultrasonic wave must be efficiently and precisely radiated on a thrombus portion as the diseased part, and the thrombus therapeutic effect must be monitored so that no excessive thrombus resolvent may be administered. Preferably, the treatment must be performed while precisely identifying the therapeutic effect.